A deadly blow, certainly missed by Warmerdam. White prepares to bring the rook to g4.
19... a7a5 Reinforcing the position of the bishop on b4, but accuracy is demanded by Black. 20. b2c3 A critical moment. 20... b4c3 This move loses. 21. d3f3 A mistake in reply. 21... f7g6 The move goes to the wrong side.